JP2006117045A - Front suspension device of automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front suspension device having a front-end steering gear unit capable of realizing the Ackerman geometry and ensuring the vehicle stability in the braking mode without sacrificing the riding comfort. <P>SOLUTION: The front suspension device 1 of an automobile having a front-set steering gear unit 16 comprises a suspension cross member 2, an upper arm 4, a lower arm 6, a wheel support 8, a steering gear unit 16, and a tie-rod 18 which extends in a diagonally forward direction outward of the vehicle width direction from the steering gear unit and is connected to a front end 8d of the wheel support forward of an automobile body. The upper arm is provided so that the line to connect two mounting parts extends in a diagonally forward direction inward of the vehicle width direction in plan view, and the lower arm is provided so that the line to connect two mounting parts extends in a diagonally forward direction inward of the vehicle width direction in plan view. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a front suspension apparatus for an automobile, and more particularly, to a front suspension apparatus for an automobile provided with a front steering gear unit.

  2. Description of the Related Art In recent years, a front midship vehicle is known in which an engine mounting position is close to a passenger compartment side in order to improve vehicle motion performance, particularly steering stability (steering stability). In such a vehicle, the steering gear unit may need to be attached to the vehicle body on the front side of the vehicle body with respect to the engine and the suspension arm because of its layout. In the case of such a front-mounted steering gear unit, the tie rod extending from the steering gear unit is attached to the front end portion of the vehicle body of the wheel support.

  On the other hand, mainly in a double wishbone type front suspension device, an elastic bushing with increased compliance is provided at the attachment portion of each suspension arm to the vehicle body to obtain a good riding comfort. ing. In addition, so-called tickling is provided on such an elastic bush to achieve both steering stability and riding comfort. Patent Document 1 discloses a suspension device in which the angle at which a bevel (slot) is provided is adjusted in order to suppress shimmy.

European Patent No. 0653320B1

Here, as shown in FIG. 6, at the time of braking, a braking force F directed toward the rear of the vehicle body is applied to the tire 16, and a rotational moment M is applied to the wheel support 8 by this braking force F. In the double wishbone type front suspension device, when such a rotational moment M is transmitted to the suspension arms 4 and 6, the elastic bushing is deformed. When an elastic bushing with increased compliance is used, such deformation of the elastic bushing becomes large, and the upper arm 4 is displaced forward of the vehicle body and the lower arm 6 is displaced backward of the vehicle body (D1, D2 in FIG. 6). As a result, the wheel support 8 rotates in the direction D3 in FIG.
When such rotation occurs in the front-mounted steering gear unit, the vehicle body front end portion 8d of the wheel support 8 to which the tie rod is attached is displaced downward and rearward of the vehicle body.

Here, the tie rod is inclined so as to extend obliquely forward of the vehicle body in plan view in order to establish the Ackermann geometry, and further to the exterior of the vehicle body in front view to obtain bump toe-in characteristics. It is necessary to provide an inclination angle so as to extend obliquely upward.
Therefore, for example, as shown by the phantom line in FIG. 7, as the wheel support 8 rotates, the inclination angle of the tie rod 18 decreases, while the length of the tie rod itself does not change. And the vehicle body rearward side and the vehicle width direction outward. Therefore, the wheel is directed in the toe-out direction.
As described above, the tie rod 18 is attached to the vehicle body front end 8d of the wheel support 8 and the tie rod 18 is inclined, so that the wheel is directed in the toe-out direction during braking. Therefore, there is a problem that the vehicle stability at the time of braking may be lowered particularly during high-speed traveling.
On the other hand, if the compliance of the elastic bushing is reduced in order to prevent such toe-out, the riding comfort is deteriorated.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and can establish the Ackermann geometry and ensure vehicle stability during braking without sacrificing riding comfort. An object of the present invention is to provide a front suspension device including a front-mounted steering gear unit.

In order to achieve the above object, the present invention is a front suspension device for an automobile equipped with a front steering gear unit, and includes a suspension cross member fixed to a vehicle body and elastic bushes at two locations on the suspension cross member. An A-type upper arm attached to the suspension cross member, an A-type lower arm attached to the suspension cross member via elastic bushes at two locations, an upper portion thereof attached to the upper arm, and a lower portion thereof attached to the lower arm, respectively. A wheel support that is rotatably supported, a steering gear unit that is fixed at a position in front of the vehicle body from the upper arm and lower arm of the suspension cross member, and a steering gear that extends obliquely forward from the steering gear unit outward in the vehicle width direction. The upper arm has two mounting portions, and the line connecting them is obliquely forward inward in the vehicle width direction in plan view. The lower arm is characterized in that two attachment portions are provided so that a line connecting them extends obliquely forward inward in the vehicle width direction in a plan view.
In the present invention configured as described above, the steering gear unit is fixed at a position in front of the vehicle body from the upper arm and the lower arm of the suspension cross member, and the tie rod is obliquely forward outward from the steering gear unit in the vehicle width direction. The steering gear unit is connected to the front end of the vehicle body of the wheel support. The Ackermann geometry can be established by the tie rod configured as described above. On the other hand, in such a tie rod configuration, the front end of the vehicle body of the wheel support is displaced outward in the vehicle width during braking because the upper arm and the lower arm are attached to the suspension cross member via the elastic bush. Then the wheels turn in the toe-out direction. However, the upper arm is provided with two mounting portions so that the line connecting them extends obliquely forward in the vehicle width direction in plan view, and the lower arm has two mounting portions connecting them. Since the line is provided so as to extend obliquely forward in the vehicle width direction in plan view, during braking, the upper arm is displaced inward in the vehicle width direction as the vehicle body is displaced forward, and the lower arm is It is displaced outward in the vehicle width direction along with the rearward displacement of the vehicle body. Accordingly, the upper portion of the wheel support is displaced inward in the vehicle width direction, the lower portion of the wheel support is displaced outward in the vehicle width direction, and the wheel is tilted in the direction of the negative camber in the vehicle width direction. By such a negative camber, a force acting inward in the vehicle width direction acts on the wheel, and a force directed outward in the vehicle width direction acting on the wheel by toe-out can be canceled. As a result, even when the compliance of the elastic bushing is increased to ensure riding comfort, vehicle stability during braking can be obtained.

In the present invention, it is preferable that the elastic bush of the mounting portion on the vehicle rear side of the lower arm is provided so that the central axis extends in the vehicle body vertical direction, and the elastic bush extends in the vehicle width direction in plan view. It has a straight portion formed in a region in front of the vehicle body from the axis and inward of the vehicle body from the axis extending in the vehicle longitudinal direction.
In the present invention configured as described above, the elastic bush provided so that its central axis extends in the vehicle vertical direction is an axis extending in the vehicle front side and in the vehicle longitudinal direction from the axis extending in the vehicle width direction in plan view. Since it has a straight portion formed in a region on the inner side of the vehicle body, the elastic bush is deformed in an oblique direction rearward of the vehicle body and outward in the vehicle width direction during braking. Along with such deformation, the attachment portion of the lower arm to the wheel support can be displaced outward in the vehicle width direction, so that the wheel can be tilted more reliably in the direction in which the negative camber is attached. During braking, the front end of the vehicle body of the wheel support is displaced outward in the vehicle width direction as described above, and the attachment portion of the lower arm to the wheel support is also displaced outward in the vehicle width direction due to deformation of the elastic bush. It will be. In this way, the wheel support can be moved outward in the vehicle width direction as a whole, and toe-out itself during braking of the wheels can be suppressed.

In the present invention, it is preferable that the upper arm and the lower arm have directions in which a line connecting the two attachment portions of the upper arm and a line connecting the two attachment portions of the lower arm are substantially orthogonal to the direction in which the tie rod extends. It is arrange | positioned so that it may extend.
In the present invention configured as described above, the upper arm and the lower arm have a line connecting the two attachment portions of the upper arm and a line connecting the two attachment portions of the lower arm, respectively, substantially orthogonal to the direction in which the tie rod extends. Since the wheels are arranged so as to extend in the direction in which the camber moves, the wheels can be tilted more effectively in the direction in which the negative camber is attached.

In addition, the present invention preferably further includes a stopper that is provided at the lower arm mounting portion and suppresses the displacement of the lower arm forward of the vehicle body due to the deformation of the elastic bush of the lower arm.
In the present invention configured as described above, since there is a stopper that is provided at the lower arm mounting portion and suppresses the displacement of the lower arm forward of the vehicle body due to deformation of the elastic bush of the lower arm, lateral force is applied to the suspension device during traveling. Even if a compression force is applied to the lower arm, the lower arm is displaced forward due to the fact that the line connecting the two mounting portions of the lower arm extends obliquely forward in the vehicle width direction in plan view. Can be prevented. Here, when the lower arm is displaced forward of the vehicle body, the tie rod extends obliquely forward outward in the vehicle width direction and is attached to the vehicle body front end of the wheel support, so that the wheel faces the toe-out direction, In the present invention, this can be prevented. As a result, it is possible to prevent the operability from being lowered.

In addition, the present invention preferably further includes a stopper that is provided at the mounting portion of the upper arm and suppresses the displacement of the upper arm toward the rear of the vehicle body due to the deformation of the elastic bush of the upper arm.
In the present invention configured as described above, since the stopper further is provided at the mounting portion of the upper arm and suppresses the displacement of the upper arm to the rear of the vehicle body due to the deformation of the elastic bushing of the upper arm, Even if a force is applied and a tensile force is applied to the upper arm, the upper arm is displaced rearward because the line connecting the two attachment portions of the upper arm extends obliquely forward in the vehicle width direction in plan view. Can be prevented. Here, when the upper arm is displaced to the rear of the vehicle body, the tie rod extends obliquely forward in the vehicle width direction outward and is attached to the vehicle body front end of the wheel support, so that the wheel faces the toe-out direction, In the present invention, this can be prevented. As a result, it is possible to prevent the operability from being lowered.

  According to the front suspension device of the present invention, even if the steering gear unit is a front-end type, the Ackermann geometry can be established and the vehicle stability during braking can be ensured without sacrificing riding comfort.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, the front suspension apparatus 1 will be described with reference to FIG. FIG. 1 is a perspective view showing a front suspension apparatus for an automobile according to an embodiment of the present invention.
A front suspension device 1 according to an embodiment of the present invention is attached to a suspension cross member 2 fixed to a vehicle body (not shown). The suspension cross member 2 includes a U-shaped front member 2a extending in the vehicle width direction and extending from both sides toward the rear of the vehicle body, and an upper member 2b extending upward fixed to both sides of the front member 2a in the vehicle width direction. The rear member 2c extends in the vehicle width direction behind the front member 2a, and both end portions thereof are fixed to the front member 2a.

  The front suspension apparatus 1 is a double wishbone type, and includes an upper arm 4 attached to the upper member 2b, a lower arm 6 attached to the front member 2a, a wheel support 8 attached to these upper arm 4 and lower arm 6, and A shock absorber 10 is provided. The wheel support 8 rotatably supports the front wheel 16 (see FIG. 3), the brake disc 18 and the like. The shock absorber 10 includes a damper 12 and a coil spring 14, the upper ends of which are fixed to a vehicle body (not shown), and the lower end of the damper 12 is attached to the lower arm 6.

  Further, the front suspension device 1 includes a steering gear unit 16 fixed to the front member 2a so as to extend in the vehicle width direction on the front side of the suspension cross member 2, and extends outward from the steering gear unit 16 in the vehicle width direction. And a tie rod 18 attached to the wheel support 8. The steering gear unit 16 is a rack and pinion type or ball screw type steering device, and is adapted to steer the front wheels 16 via a tie rod 18.

  Next, the configuration of the front suspension apparatus 1 will be specifically described with reference to FIGS. FIG. 2 is a plan view of the right front wheel side of the front suspension device for a vehicle according to the embodiment of the present invention as viewed from above the vehicle body, and FIG. 3 shows the right front wheel side of the front suspension device for the vehicle according to the embodiment of the present invention. FIG. 4 is a front view as seen from the front of the vehicle body, FIG. 4 is a plan view showing a lower arm of a front suspension device for an automobile according to an embodiment of the present invention, and FIG. 5 is a perspective view showing a stopper according to an embodiment of the present invention. It is a) and its longitudinal cross-sectional view (b). In FIG. 2, the shock absorber 10 is not shown. Here, since the basic structure of the front suspension device of an automobile is the same on both the right front wheel side and the left front wheel side, here, description will be made mainly with reference to FIGS. 2 and 3 showing the right front wheel side.

First, the configuration of the upper arm 4 and the lower arm 6 and the configuration of the wheel support 8 to which these arms 4 and 6 are attached will be described.
As shown in FIG. 2, the upper arm 4 is an A-type arm having a front arm portion 4 a and a rear arm portion 4 b, and is attached to the upper member 2 b of the suspension cross member 2 by two attachment portions 20 and 22. Yes. In these attachment portions 20 and 22, the vehicle width direction inner end portions 4 c and 4 d of the arm portions 4 a and 4 b are attached to the vehicle body side via a cylindrical elastic bush 24. These elastic bushes 24 are provided so that the central axis thereof is parallel to a one-dot chain line A in FIG.

The lower arm 6 is an A-type arm having a front arm portion 6a that extends substantially in the vehicle width direction and a rear arm portion 6b that extends obliquely forward in the vehicle width direction outward, and is suspended by two attachment portions 26 and 28. The front member 2a of the cross member 2 is attached. In these attachment portions 26, 28, the vehicle width direction inner end portions 6 c, 6 d of the arm portions 6 a, 6 b are attached to the vehicle body side via a cylindrical elastic bush 24.
The elastic bush 24 of the mounting portion 26 on the front side of the vehicle body is provided so that the central axis thereof is parallel to a one-dot chain line B in FIG. 2 described later, and the elastic bush 24 of the mounting portion 28 on the rear side of the vehicle body is A central axis is provided in the direction. Further, each of the bushes 24 provided on the lower arm 6 has a large compliance in order to ensure riding comfort. On the other hand, in order to ensure maneuverability, the elastic bushing 24 of the mounting portion 26 on the front side of the vehicle body is relatively smaller in compliance than the elastic bushing 24 of the mounting portion 28 on the rear side of the vehicle body.

  The vehicle width direction outer ends 4 e and 6 e of the upper arm 4 and the lower arm 6 are attached to the wheel support 8. Specifically, as shown in FIG. 3, the wheel support 8 includes an upper arm connecting extension portion 8a extending upward and a lower arm connecting extension portion 8b extending downward. The extension portions 8a and 8b are respectively attached to the upper end portion and the lower end portion via a ball joint 30 (see FIG. 2). In FIG. 3, illustration of a part of the front arm portion 6a is omitted.

Next, the configuration of the tie rod 18 and the configuration of the wheel support 8 will be described.
As shown in FIG. 2, the wheel support 8 includes a tie rod connecting extension portion (knuckle arm) 8c extending forward of the vehicle body, and an end portion 8d of the tie rod 18 in the vehicle width direction is provided at a distal end portion 8d of the extension portion 8c. Is attached. The inner end of the tie rod 18 in the vehicle width direction is attached to the steering gear unit 16.
Here, in the front suspension apparatus 1 according to the embodiment of the present invention, the steering gear unit 16 is attached to the front of the suspension cross member 2. Therefore, the tie rod 18 is disposed in front of the arms 4 and 6, and the outer end portion in the vehicle width direction is attached to the vehicle body front end portion (the tip portion 8 d of the extension portion 8 c) of the wheel support 8. Become.

As shown in FIG. 2, the tie rod 18 extends obliquely forward in the vehicle width direction outward in a plan view, and has an inclination angle α with respect to the vehicle width direction. The inclination angle α establishes the Ackermann geometry of the front suspension device 1 so that the turning angle of the turning inner wheel is larger than the turning angle on the outer wheel side during steering.
As shown in FIG. 3, the tie rod 18 extends obliquely upward outward in the vehicle width direction when viewed from the front, and has an inclination angle β with respect to the horizontal line. By this inclination angle β, the front suspension device 1 has a bump toe-in characteristic, and the bumped turning outer ring is prevented from moving toward the toe-out.

  Here, as described above, because the tie rod 18 is attached to the front end of the vehicle body of the wheel support 8 and the tie rod 18 is inclined, the front wheel 16 is toe-out during braking. There is a tendency to turn in the direction. Therefore, in the embodiment of the present invention, the mounting portions 20 and 22 of the upper arm 4 and the mounting portions 26 and 28 of the lower arm 6 are arranged in a predetermined positional relationship, so that the wheel 16 is braked as will be described in detail later. It becomes a negative camber so as to obtain vehicle stability during braking. Further, a curving portion (low resilience portion) is provided in the elastic bush 24 of the mounting portion 28 on the vehicle body rear side of the lower arm 6 so that the wheel 16 becomes a negative camber during braking by the arrangement of the curling portion, and the front wheel 16 The toe-out itself during braking is suppressed.

First, the arrangement of the mounting portions 20 and 22 on the vehicle body side of the upper arm 4 and the mounting portions 26 and 28 on the vehicle body side of the lower arm 6 will be described.
The attachment portions 20 and 22 of the upper arm 4 are arranged so that the lines connecting them extend obliquely forward inward in the vehicle width direction in a plan view, as indicated by a one-dot chain line A in FIG. Further, the attachment portions 26 and 28 of the lower arm 6 are arranged so that the lines connecting them extend obliquely forward inward in the vehicle width direction in a plan view, as shown by a one-dot chain line B in FIG. . The line A connecting the mounting portions 20 and 22 of the upper arm 4 and the line B connecting the mounting portions 26 and 28 of the lower arm 6 are both substantially orthogonal to the extending direction of the tie rod 18 in plan view. It extends to.

Here, when a lateral force is input from the wheel 16 to the suspension device 1 during traveling, the upper arm 4 and the lower arm 6 are respectively arranged on the rear side of the vehicle body due to the arrangement of the mounting portions 20, 22, 26, and 28. Or it becomes easy to displace to the vehicle body front. Therefore, in the present embodiment, in order to suppress these displacements, stoppers 40 are provided on the attachment portion 22 and the attachment portion 26.
As shown in FIG. 2, a stopper 40 that suppresses the displacement of the upper arm 4 toward the rear of the vehicle body due to the deformation of the elastic bushing 24 is provided at the mounting portion 22 on the rear side of the vehicle body of the upper arm 4. As shown in FIGS. 2 and 4, the mounting portion 26 on the vehicle body front side of the lower arm 6 is provided with a stopper 40 that suppresses the displacement of the lower arm 6 toward the vehicle body due to deformation of the elastic bush 24. .

Specifically, as shown in FIG. 5, each of these stoppers 40 includes a flat plate member (washer member) 42 extending in an annular shape and an elastic member 44 fixed to the flat plate member 42. Yes. The flat plate member 42 is formed with a through hole 42a through which a bolt (not shown) for fixing the elastic bush 24 to the vehicle body side passes. The elastic member 44 extends in an annular shape around the through hole 42a, and its cross section is semicircular. As shown in FIGS. 2 and 4, the stoppers 40 of the stoppers 40 are fixed to the suspension cross member 2, and the elastic members 44 are provided in the vehicle width direction inner end 4 d of the upper arm 4 and the vehicle of the lower arm 6. Each is in contact with the inner end 6c in the width direction.
Similarly, a stopper 40 that suppresses the displacement of the upper arm 4 toward the rear of the vehicle body is similarly provided at the mounting portion 20 of the upper arm 4, and the stopper 40 that suppresses the displacement of the lower arm 6 toward the front of the vehicle body is similarly provided at the mounting portion 28 of the lower arm 6. May be provided.

Next, with reference to FIG. 4, the configuration of the attachment portion 28 on the vehicle rear side of the lower arm 6 and the shape of the elastic bush 24 will be described.
First, the inner end 6d in the vehicle width direction of the lower arm 6 is formed in a cylindrical shape so as to have a central axis C (see FIG. 3) in the vertical direction of the vehicle body, and the central axis C (in FIG. The elastic bushing 24 is press-fitted so as to have 3). A metal inner cylinder portion 32 is bonded to the surface of the inner peripheral portion of the elastic bush 24, and the inner cylinder portion 32 is fixed to the vehicle body side, that is, the suspension cross member 2.

The elastic bush 24 is formed with two straight portions (low elastic portions) 34 (34a, 34b) extending along the outer peripheral portion thereof. These straight portions 34 are through holes extending in parallel with the central axis C of the elastic bushing 24. Since the portions provided with the straight portions 34 are more easily bent than the other portions, the elastic bush 24 connects the straight portions 34 and the central axis C when receiving a force from the end 6d of the lower arm. It is easy to deform in the direction on the line.
Among these straight portions 34, the first straight portion 34 a is located in the vehicle width direction from the vehicle longitudinal axis D of the elastic bushing 24 (or a neutral surface extending through the central axis C in the vehicle longitudinal direction) in plan view. It is formed in a region 24a on the front side of the vehicle body from the vehicle width direction axis E of the elastic bush 24 (or a neutral surface extending in the vehicle width direction passing through the center axis C).

  The second curb portion 34b is in the vehicle width direction outward side of the vehicle body longitudinal axis D (or the neutral surface extending through the center axis C in the vehicle longitudinal direction) of the elastic bush 24 in plan view and in plan view. The elastic bush 24 is formed in a region 24b on the rear side of the vehicle body from the vehicle width direction axis E (or a neutral surface passing through the center axis C and extending in the vehicle width direction). The second straight part 34b is formed opposite to the first straight part 34a at a position symmetric with respect to the central axis C of the elastic bush 24. Therefore, the elastic bushing 24 is easily deformed in the direction connecting the straight portions 34a and 34b.

In the straight portions 34a and 34b, the longitudinal intermediate portion along the outer peripheral portion of the elastic bush 24 is located at a position of 25 to 35 degrees (angle γ in FIG. 4) from the vehicle body longitudinal axis D in plan view. It is formed to become. In other words, the line connecting the central axis C of the elastic bush 24 and the intermediate portion in the longitudinal direction of the straight portions 34a and 34b is 25 to 35 degrees (angle γ) with respect to the longitudinal axis D of the vehicle body in plan view. Straight portions 34a and 34b are formed so as to be inclined. In the present embodiment, the angle γ is 30 degrees.
Further, the straight portions 34a and 34b are formed so that one end in the longitudinal direction thereof is located at 0 to 5 degrees from the vehicle body longitudinal axis D, and is 0 degrees in the present embodiment.
The straight portions 34a and 34b are formed so that the longitudinal direction thereof extends in a direction substantially parallel to the direction in which the tie rod 18 extends. That is, the angle γ and the inclination angle α are substantially the same.

Next, the operation of the above-described embodiment will be described with reference to FIGS. 4 and 6 to 9.
FIG. 6 is a conceptual view of a part of the suspension device for explaining the force and displacement applied to the wheel, suspension arm and wheel support during braking as seen from the side in the vehicle width direction, and FIG. 7 shows the wheel during braking. FIG. 8 is a conceptual diagram of the right front wheel side portion of the suspension device for explaining the toe-out displacement of the support as viewed from above the vehicle body, and FIG. 8 illustrates the operation of the suspension arms and their mounting portions according to the embodiment of the present invention. FIG. 9 is a conceptual diagram (a) of the right front wheel side portion of the suspension device for performing the above operation, and a conceptual diagram (b) of the suspension device viewed from the rear of the vehicle body, and FIG. 9 is a vehicle rear side of the lower arm according to the embodiment of the invention Suspension for explaining the displacement of the suspension arm, wheel support and tie rod during braking due to the action of the elastic bush It is a conceptual view of the right front wheel side portion of the location from the upper side of the vehicle body.

In order to specifically describe the operation of the present embodiment, first, the force acting on the front suspension device 1 during braking and the displacement of each part will be described with reference to FIGS.
First, as shown in FIG. 6, at the time of braking, a braking force F is applied to the wheel 16, this braking force F is transmitted to the wheel support 8, and a rotational moment force M is applied to the wheel support 8. The rotational moment force M is transmitted to the upper arm 4 and the lower arm 6, and the transmitted force deforms the elastic bush 24 of each attachment portion of the arms 4 and 6 on the vehicle body side. As a result, the upper arm 4 is displaced toward the front of the vehicle body (D1 in the figure), the lower arm 6 is displaced toward the rear of the vehicle body (D2 in the figure), and the wheel support 8 is in a direction as indicated by D3 in the figure. Rotating displacement. When the compliance of the elastic bush 24 is large, such displacements D1, D2, and D3 are particularly likely to occur. When such a rotational displacement D3 occurs in the wheel support 8, the tip 8d of the extension portion (knuckle arm) 8c for connecting the tie rod is displaced downward and rearward of the vehicle body.

  As shown in FIG. 7, the tie rod 18 is displaced as indicated by a virtual line in the drawing by such a displacement of the tip 8 d of the extension 8 c. That is, since the tip 8d is displaced downward and rearward of the vehicle body, the inclination angle (α) of the tie rod 18 is reduced, while the length of the tie rod 18 itself is not changed, so that the tip 8d is In addition, it is displaced to the rear side of the vehicle body and is also displaced outward in the vehicle width direction. That is, because the tie rod 18 is attached to the front end of the vehicle body of the wheel support 8 and the tie rod 18 is inclined, the front wheel 16 faces the toe-out direction during braking. Vehicle stability during braking may be reduced.

Next, the operation of the arrangement of the mounting portions 20, 22, 26, and 28 of the upper arm 4 and the lower arm 6 on the vehicle body, which can prevent such a decrease in vehicle stability during braking, will be described.
In the embodiment of the present invention, as shown in FIGS. 2 and 8 (a), the attachment portions 20 and 22 of the upper arm 4 are arranged so that the line connecting them extends obliquely forward inward in the vehicle width direction in plan view. Further, the attachment portions 26 and 28 of the lower arm 6 are arranged so that the lines connecting them extend obliquely forward inward in the vehicle width direction in plan view.
Therefore, as shown in FIG. 8A, when the upper arm 4 is displaced forward of the vehicle body as indicated by the phantom line (see D1 in FIG. 6), the attachment portion 4e of the upper arm 4 to the wheel support 8 is in plan view. , It moves from the position indicated by the white circle in the figure to the position indicated by the black circle, and is displaced not only in front of the vehicle body but also inward in the vehicle width direction. On the other hand, when the lower arm is displaced rearward as indicated by the phantom line (see D2 in FIG. 6), the attachment portion 6e of the lower arm 6 to the wheel support 8 is a black circle from the position indicated by the white circle in the drawing in plan view. It moves to the indicated position and displaces in the vehicle width direction outward direction as well as the rear of the vehicle body.

Here, as shown in FIG. 3 and FIG. 8B, the upper arm 4 is attached to the upper side of the wheel support 8 and the lower arm 6 is attached to the lower side of the wheel support 8. The upper side of the support 8 is displaced inward in the vehicle width direction, and the lower side of the wheel support 8 is displaced outward in the vehicle width direction. As a result, the wheel 16 is inclined in the direction of the negative camber in the vehicle width direction.
By such a negative camber, a force directed inward in the vehicle width direction is exerted on the wheel 16, so that the force directed outward in the vehicle width direction exerted on the wheel 16 by toe-out can be canceled out. As a result, vehicle stability during braking can be obtained.
Further, the line connecting the attachment portions 20 and 22 of the upper arm 4 and the line connecting the attachment portions 26 and 28 of the lower arm 6 both extend in a direction substantially orthogonal to the direction in which the tie rod 18 extends in plan view. Therefore, the vehicle stability during braking can be obtained more effectively by tilting the wheel in the direction in which the negative camber is attached.

Next, the operation of the elastic bushing 24 of the mounting portion 28 on the vehicle body rear side of the lower arm 6 that can prevent a decrease in vehicle stability during braking due to the toe-out of the front wheels 16 described above will be described.
In the embodiment of the present invention, the first curb portion 34a is arranged in the vehicle width direction inner side of the vehicle body longitudinal direction axis D of the elastic bush 24 in the plan view and in the vehicle width direction axis of the elastic bush 24 in the plan view. Since it is formed in the region 24a on the front side of the vehicle body from E, the front wheel 16 can be more reliably tilted in the direction in which the negative camber is attached.
That is, as shown in FIG. 4, the elastic bush 24 is deformed by receiving a force between the inner cylinder portion 32 on the vehicle body side and the end portion 6 d of the lower arm 6, and particularly with respect to the central axis C thereof. It is easy to deform along the direction in which the straight portion 34a is provided. Therefore, the end 6d of the lower arm 6 on the vehicle body rear side is easily displaced in a direction as indicated by D4 in FIG.

Accordingly, as shown in FIG. 9, when the lower arm is displaced rearward of the vehicle body as indicated by the phantom line (see D2 in FIG. 6), the end 6d is displaced rearward of the vehicle body and also outward in the vehicle width direction. To do. The end portion 6c on the vehicle body front side of the lower arm 6 is also displaced so as to be pulled outward in the vehicle width direction due to the displacement of the end portion 6d. Accordingly, the attachment portion 6e of the lower arm 6 to the wheel support 8 is displaced rearward of the vehicle body in the longitudinal direction of the vehicle body and is also displaced outward in the vehicle width direction. In this way, the lower side of the wheel support 8 can be more reliably displaced outward in the vehicle width direction, and as a result, the front wheel 16 can be more reliably tilted in the direction in which the negative camber is attached, thereby Stability can be obtained.
Further, the second curb portion 34b is in the vehicle width direction outward side with respect to the vehicle body longitudinal axis D of the elastic bush 24 in plan view, and the vehicle body rear side with respect to the vehicle width direction axis E of the elastic bush 24 in plan view. In the region 24b, the elastic bush 24 of the mounting portion 28 on the rear side of the vehicle body is greatly deformed along the direction connecting the straight portions 34a and 34b. This facilitates and more reliably displaces the lower side of the wheel support 8 outward in the vehicle width direction and tilts the wheel 16 in the direction in which the negative camber is attached.

Next, the operation of the stopper 40 will be described.
First, during traveling, when the wheel 16 receives a lateral force from the ground and the lateral force is input to the suspension device 1, a force (compression force) directed inward in the vehicle width direction is exerted on the lower arm 6 due to the lateral force. Join. Further, the wheel support 8 has a rotational force that tilts in the vehicle width direction with the mounting portion 6e of the lower arm 6 attached to the wheel support 8 as a fulcrum, and the upper arm 4 has a force that pulls outward (tensile force). ) Is added.
As described above, the attachment portions 20 and 22 of the upper arm 4 and the attachment portions 26 and 28 of the lower arm 6 are such that the lines connecting the attachment portions extend obliquely forward inward in the vehicle width direction in plan view. Therefore, the lower arm 6 tends to displace to the front of the vehicle body due to the compression force, and the upper arm 4 tends to displace to the rear of the vehicle body due to the tensile force.

When such a displacement of the lower arm 6 toward the front of the vehicle body and a displacement of the upper arm 4 toward the rear of the vehicle body occur during traveling, the tip 8d of the extension portion 8c of the wheel support 8 is displaced upward and toward the rear of the vehicle body. Similarly to the operation described in (4), due to the inclination angle of the tie rod 18, the wheels 16 are directed in the toe-out direction, resulting in a decrease in maneuverability.
In the present embodiment, a stopper 40 that suppresses displacement of the upper arm 4 toward the rear of the vehicle body due to deformation of the elastic bushing 24 is provided at the mounting portion 22 on the rear side of the vehicle body of the upper arm 4. Since the mounting portion 26 is provided with a stopper 40 that suppresses the displacement of the lower arm 6 toward the front of the vehicle body due to the deformation of the elastic bush 24, the wheel 16 can be suppressed from moving in the toe-out direction during traveling. Safety can be secured.

Next, a further function of the elastic bushing 24 of the mounting portion 28 on the vehicle rear side of the lower arm 6 that can suppress the toe-out of the front wheel 16 at the time of braking described above will be described.
In the embodiment of the present invention, the first curb portion 34a is arranged in the vehicle width direction inner side of the vehicle body longitudinal direction axis D of the elastic bush 24 in the plan view and in the vehicle width direction axis of the elastic bush 24 in the plan view. Since it is formed in the region 24a on the front side of the vehicle body from E, toe-out itself during braking of the front wheels 16 can be suppressed.

That is, as described above, the end 6d of the lower arm 6 on the vehicle body rear side is easily displaced in the direction as indicated by D4 in FIG. 4, so that the wheel support 8 of the lower arm 6 as shown in FIG. The mounting portion 6e is displaced rearward in the vehicle front-rear direction and is also displaced outward in the vehicle width direction.
In other words, due to the rotational displacement during braking of the wheel support 8 (see D3 in FIG. 6), even if the tip 8d is displaced outward in the vehicle width direction due to the inclination angle of the tie rod 18, the lower arm 6 The attachment portion 6e to the wheel support 8 is also displaced outward in the vehicle width direction. As a result, as indicated by the phantom line in FIG. 9, the wheel support 8 moves as a whole outward in the vehicle width direction, and toe-out itself during braking of the front wheels 16 can be suppressed.

  Further, since the elastic bush 24 of the mounting portion 26 on the front side of the vehicle body has a relatively small compliance with respect to the elastic bush 24 of the mounting portion 28 on the rear side of the vehicle body, as shown by the phantom line in FIG. 6 also causes rotation about the mounting portion 26 on the front side of the vehicle body. Due to this rotation, the attachment portion 6e of the lower arm 6 to the wheel support 8 is displaced forward of the vehicle body, so that the attachment portion 6e of the attachment portion 6e is displaced rearward by the displacement of the lower arm 6 by the braking force F (see D2 in FIG. 6). Therefore, the rotational displacement D3 (see FIG. 6) of the wheel support 8 can also be suppressed. As a result, toe-out during braking of the front wheels 16 can be suppressed.

Next, in the embodiment of the present invention, the second curb portion 34b has the vehicle of the elastic bush 24 in the vehicle width direction outward side from the vehicle body longitudinal axis D of the elastic bush 24 in plan view and in plan view. Since it is formed in the region 24b on the vehicle body rear side from the width direction axis E so as to face the first curb portion 34a, the elastic bush 24 of the mounting portion 28 on the vehicle body rear side connects the curb portions 34a, 34b to each other. It becomes easy to greatly deform along the connecting direction, and toe-out during braking of the front wheels 16 can be suppressed more reliably.
Further, each of the straight portions 34a and 34b extends along the outer peripheral portion of the elastic bush 24, and an intermediate portion in the longitudinal direction thereof is 25 to 35 degrees from the vehicle body longitudinal axis D in plan view (angle γ in FIG. 4). Therefore, while the toe-out at the time of braking of the front wheels 16 is suppressed, the amount of deformation of the elastic bush 24 in the longitudinal direction of the vehicle body is made relatively large to ensure the riding comfort. At the same time, it is possible to ensure the operability by preventing the amount of deformation in the vehicle width direction from becoming excessively large.

Further, the straight portions 34a and 34b are formed so that one end in the longitudinal direction thereof coincides with the vehicle body longitudinal axis D, that is, at a position of 0 to 5 degrees from the vehicle longitudinal axis D. It is possible to more reliably achieve both ride comfort and maneuverability while suppressing toe-out during braking 16.
Further, the straight portions 34a and 34b are formed so that their longitudinal directions extend in the direction in which the tie rod 18 extends, that is, in a direction substantially parallel to the direction of the inclination angle α with respect to the vehicle width direction in plan view. More effectively, toe-out during braking can be suppressed.

1 is a perspective view showing a front suspension device for an automobile according to an embodiment of the present invention. It is the top view which looked at the right front-wheel side of the front suspension apparatus of the motor vehicle by embodiment of this invention from the vehicle body upper direction. It is the front view which looked at the right front-wheel side of the front suspension apparatus of the motor vehicle by embodiment of this invention from the vehicle body front. It is a top view which shows the lower arm of the front suspension apparatus of the motor vehicle by embodiment of this invention. It is the perspective view (a) which shows the stopper by embodiment of this invention, and its longitudinal cross-sectional view (b). It is the conceptual diagram which looked at a part of suspension apparatus for demonstrating the force and displacement which are added to a wheel, a suspension arm, and a wheel support at the time of braking from the vehicle width direction side. It is the conceptual diagram which looked at the right front-wheel side part of the suspension apparatus for demonstrating the toe-out displacement of the wheel support at the time of braking resulting from the inclination angle of a tie rod, and the attachment position to the wheel support of a tie rod from the vehicle body upper direction. The conceptual diagram which looked at the right front-wheel side part of the suspension apparatus for demonstrating the effect | action by arrangement | positioning of the suspension arm by those embodiment of this invention, and those attachment parts, and the conceptual diagram which looked from the vehicle body rear (b) ). FIG. 3 is a conceptual diagram of a right front wheel side portion of a suspension device for explaining displacements during braking of a suspension arm, a wheel support, and a tie rod caused by an action of an elastic bush on the vehicle body rear side of a lower arm according to an embodiment of the present invention when viewed from above the vehicle body. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front suspension apparatus 2 Suspension cross member 4 Upper arm 6 Lower arm 8 Wheel support 10 Cushioning device 16 Front wheel 20 The attachment part of the upper arm to the vehicle body front side 22 The attachment part of the upper arm to the vehicle body rear side of the vehicle body 24 Elastic bushing 26 Lower arm Attachment portion on the front side of the vehicle body to the vehicle body 28 Attachment portion on the rear side of the vehicle body on the vehicle body of the lower arm 34 Straightening portion 40 Stopper

Claims (5)

A front suspension device for an automobile equipped with a front-mounted steering gear unit,
A suspension cross member fixed to the vehicle body,
An A-type upper arm attached to the suspension cross member via elastic bushes at two locations;
An A-type lower arm attached to the suspension cross member via elastic bushes at two locations;
A wheel support whose upper part is attached to the upper arm and whose lower part is attached to the lower arm, respectively, and supports the wheel rotatably;
A steering gear unit fixed at a position in front of the vehicle body from the upper arm and the lower arm of the suspension cross member;
A tie rod extending diagonally forward from the steering gear unit outward in the vehicle width direction and connecting the steering gear unit and the front end of the wheel support body;
The upper arm is provided such that the two attachment portions are provided so that a line connecting them extends obliquely forward in the vehicle width direction in plan view, and the lower arm includes the two attachment portions. A front suspension device for an automobile, wherein the connected line is provided so as to extend obliquely forward inward in the vehicle width direction in plan view.   The elastic bush of the mounting portion on the vehicle body rear side of the lower arm is provided such that its central axis extends in the vertical direction of the vehicle body. 2. The front suspension device for an automobile according to claim 1, further comprising a straight portion formed in a region inside the vehicle body from an axial line extending in the direction.   In the upper arm and the lower arm, a line connecting the two attachment portions of the upper arm and a line connecting the two attachment portions of the lower arm respectively extend in a direction substantially orthogonal to a direction in which the tie rod extends. The front suspension apparatus for an automobile according to claim 1 or 2, which is arranged as described above.   4. The front suspension device for an automobile according to claim 1, further comprising a stopper that is provided at an attachment portion of the lower arm and suppresses displacement of the lower arm forward of the vehicle body due to deformation of an elastic bushing of the lower arm. .   5. The front suspension device for an automobile according to claim 1, further comprising a stopper that is provided at a mounting portion of the upper arm and suppresses displacement of the upper arm toward the rear of the vehicle body due to deformation of the elastic bushing of the upper arm. .

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